In a number of industries, there arises a need to slice or cut various thin planar materials such as plastics or the like. In many cases, these materials are made more difficult to cut due to their thinness and their fabrication from elastic or stretchable materials. One of the materials found to be extremely difficult to cut is the self-adhesive plastic or vinyl sheet material used for labeling, signs, and decoration of various surfaces. Generally, such vinyl or plastic material is formed in a single thin sheet having an adhesive coating on one side which is layered upon a firmer carrier material such as paper. The vinyl or plastic material is cut to the desired shape and then removed from the paper carrier material by peeling the cut portion away from the supporting carrier layer. Because it is often desired to cut such vinyl or plastic material into relatively complex shapes such as letters or designs and because the material is elastic or stretchable, cutting is often a difficult and tedious process. In many instances, such materials are cut by hand using templates or the like in a process which is extremely costly and somewhat inaccurate. In addition, hand cutting is a slow process and requires considerable skill.
The need for better and less costly methods of cutting such thin vinyl or plastic materials has prompted practitioners in the art to make various attempts at creating automated systems for cutting these materials. One of the most promising type of automated cutting system is that which generally resembles a graphic recorder or plotter. In such systems a cutting blade assembly is movably supported upon a track mechanism and is movable back and forth along the track to define a blade path. Means are provided for supporting the cutting blade and for lowering the blade into a cutting position and raising it to a noncutting position. In addition, the blade control mechanism is operative to rotate the cutting blade to provide material cuts in various directions. A media supporting system is positioned beneath the blade carriage track and is operative to support the material and to move the material with respect to the blade carriage path. In most instances, the material is formed to include a plurality of sprocket drive holes adjacent each edge of the material and the sprocketed drive means engage the sprocket holes to control and move the material during the cutting process. In most instances, the directions of blade carriage motion and media motion are mutually perpendicular. Automatic control means, usually including a computer, are operative to coordinate the position of the blade carriage, the blade rotation, and the material movement to produce the desired cuttings of the material.
While such systems have enjoyed some success and provide substantial improvement in many instances over the more costly time consuming hand cutting operations, several problems remain in need of further improvement. One of the more pressing problems in optimizing such automated cutting systems arises in the cutting characteristics of the blade itself. As mentioned, the material is, in many instances, elastic and easily stretched with respect to its supporting medium. As a result, failures of the cutting blade to cleanly slice the material, result in stretching or deforming the material and degrading the quality and accuracy of the cut material piece. In addition, the depth of cut must be carefully controlled to avoid cutting the supporting material while simultaneously assuring a clean cut through the entire material layer.
There arises, therefore, a need for an automatically controllable sheet slicing mechanism which easily and accurately positions and rotates the cutting blade in a sheet slicing mechanism and which accurately maintains the desired depth of material cut.